This invention relates generally to contactors, and more particularly to contactor movement and arc reduction in lighting contactor block assemblies.
Contactor block assemblies refer to single or multiple pole power switching devices located in a branch circuit, used to switch (make or break) one or more pieces of equipment. Frequently, automated lighting control applications use contactor block assemblies that include fixed and moving contacts. Lighting contactor block assemblies can be differentiated by many characteristics, including, but not limited to, lighting load type, load current, contact holding method, lighting contactor type, and number of poles. Further features include enclosure type, pole configuration, fusing type, control circuit, indicating lights, and auxiliary contacts.
In the past, contactor block assemblies were generally placed near the controlled equipment. In some applications, however, contactor block assemblies are located in a central cabinet located in an electrical equipment room near a panelboard. A shortened conductor length between the panelboard and the contactor block assembly central cabinet increases a fault current at the contactor. Regardless of the contractor assembly location, during a short circuit a large and rapid influx of electromagnetic energy pushes a moving contact in the lighting contactor away from a fixed contact. As the moving contact separates from the fixed contact an arc forms, causing an energy release. As the arc length grows longer, more energy is released. In some short circuits, the energy release is sufficient to breakdown plastic components in the contactor block assembly causing out-gassing. The out-gassing can result in physical damage to the contactors, contactor block assemblies and the central cabinet.